Micro-turbulence in the solar wind at 5-76 Rs observed with interplanetary scintillation

Yohei Yamauchi, Masayoshi Kojima, Munetoshi Tokumaru, Hiroaki Misawa, Hirotaka Mori, Takashi Tanaka, Hiroshi Takaba, Tetsuro Kondo, P. K. Manoharan

Research output: Contribution to journalArticlepeer-review

Abstract

We study the properties of micro-turbulence in the solar wind using interplanetary scintillation (IPS) observations made with the single dish antenna operating at 2.3 GHz and 8.5 GHz. Our IPS observations were made during September-October in 1992 and 1993 and covered a radial distance range of 5-76 solar radii (Rs). We apply the spectral-fitting method to obtain properties of solar wind turbulence, such as axial ratio of anisotropy, inner scale of dissipation length, power-law spectral index, and solar wind velocity. We also examine the velocity dependence of the turbulence near the sun, and find the following results. (1) Both low-speed and high-speed solar-wind flows show acceleration at the distance range of 10-30 Rs, which is consistent with previous works. (2) The radial dependence of anisotropy and spectral index show no significant difference between the low-speed and high-speed solar wind. (3) Only the inner scale length shows a dependence on flow speed: the inner scale in the high-speed wind is 1.4 ± 0.3 times larger than that in the low-speed wind.

Original languageEnglish
Pages (from-to)1201-1217
Number of pages17
Journalearth, planets and space
Volume48
Issue number10
DOIs
Publication statusPublished - 1996

ASJC Scopus subject areas

  • Geology
  • Space and Planetary Science

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